1. Field of the Invention
The present invention relates to drums, that is to say percussion instruments, such as snare drums, tom-toms, bass drums, tympanis, and the like. The invention is particularly concerned with the tuning of drum heads.
2. Description of Related Art
In conventional drums, the skin of the drum head is stretched over the open end of a cylindrical drum shell and is held in position by means of a counter-hoop which bears on the rim of the head. The skin is tensioned by means of tensioning bolts which act on the counter-hoop and engage tapped fittings fixed to the drum shell. When these bolts are tightened, the counter-hoop is urged against the rim, thus tensioning the skin.
In order to ensure that the skin is evenly tensioned and is therefore "tuned", it is necessary to adjust minutely each of the bolts, which are usually at least six or eight in number. This procedure is complicated by the fact that when one bolt is adjusted it has differing effects on the tension in the skin produced by the other bolts, making tuning a very time consuming and skilled operation.
Two related proposals which seek to address this disadvantage are described in British Patent Nos. 1488167 and 1558045. In the first of these references, the counter-hoop has a series of circumferentially located inclined slides which each engage a pair of rollers which are fixed to the shell. The rollers in each pair are offset to define an angle of inclination which corresponds to the inclination of the slides. Thus, as the counter-hoop is rotated in one sense, the slides and rollers engage, drawing the counter hoop down against the head rim and so tensioning the head. Rotation in the other sense has the opposite effect. The counter-hoop is rotated by means of a rack which is fixed to the counter-hoop, and a pinion fixed to the shell; as the pinion is rotated, the rack is driven circumferentially. The arrangement shown in the second reference is very similar except that the rollers are replaced by inclined nylon blocks.
A disadvantage of these arrangements is that even tensioning is still difficult to achieve in practice, partly due to unevenness and imperfections in the heads and partly due to the difficulties in attaching the rollers or blocks accurately to the shell.
This problem is addressed in the present Applicant's co-pending application No. 9511862.6 which provides a drum comprising: a drum shell; a drum head having a skin extending over an open end of the shell and a circumferential hoop lying outside the open end of the shell; a counter-hoop lying over the head hoop, the counter-hoop having a plurality of circumferentially-spaced inwardly-facing cam followers; and means for rotating the counter-hoop about the drum axis with respect to the drum shell; the drum also including a shell ring attached to and surrounding the shell in the vicinity of the open end and a compression ring located between the counter-hoop and the head hoop; the shell ring having a plurality of circumferentially-spaced, outwardly facing cam members which respectively engage the counter-hoop cam followers.
However, a simpler arrangement may be advantageous in certain circumstances. It is therefore an object of the present invention to provide a drum in which the drum skin can be tensioned and tuned in a single operation and which is simpler in construction than existing designs.